System and method for monitoring the status of one or more components of an electrical machine

ABSTRACT

A system for monitoring the wear state of a carbon brush of a brush holder assembly in which the length of the carbon brush is diminished from an initial length as an end of the carbon brush wears away during use. The system includes a wear state monitor, including a sensor, coupled to the carbon brush. The wear state monitor is configured to rotate as the length of the carbon brush diminishes. The sensor is configured to measure an angular displacement of the wear state monitor as the wear state monitor rotates. The measured angular displacement of the wear state monitor correlates to an amount of diminution in the length of the carbon brush.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. § 119 toU.S. Provisional Application Ser. No. 62/741,152, filed Oct. 4, 2018,the entirety of which is incorporated herein by reference.

TECHNICAL FIELD

The disclosure generally relates to monitoring systems for monitoringbrushes and brush holder assemblies that may be used in electricaldevices and/or slip ring assemblies. More specifically, the disclosurerelates to monitoring apparatus, assemblies, systems and methods ofmonitoring the wear of a brush in a brush holder assembly and/or thecondition of a slip ring of an electrical device using a sensor.

BACKGROUND

A purpose of a brush in an electrical device is to pass electricalcurrent from a stationary contact to a moving contact surface, or viceversa. Brushes and brush holders may be used in electrical devices suchas electrical generators, electrical motors, and/or slip ringassemblies, or sliding connection applications, for example, slip ringassemblies on a rotating machine such as a rotating crane or a linearsliding connection on a monorail. Brushes in many electrical devices areblocks or other structures made of conductive material, such asgraphite, carbon graphite, electrographite, metal graphite, or the like,that are adapted for contact with a conductive surface or surfaces topass electrical current. Electrically conductive leads or shunts extendfrom the brush to provide an electrical pathway to and/or from the brushfrom another conductive member.

In some designs, a brush box type brush holder, or other type of brushholder, may be used to support a brush in contact with a moving contactsurface of an electrical device during operation. The brush and brushbox may be designed such that the brush can slide within the brush boxto provide for continuing contact between the brush and the movingcontact surface contacted by the brush. During operation an anomalousand/or threshold condition may occur, which may be indicative that oneor more components of the electrical device may need to be replaced, oneor more components of the electrical device may require inspection orattention, and/or maintenance may need to be performed. For example, ananomalous and/or threshold condition may indicate that one or more of abrush, brush holder, spring, shunt, commutator, collector ring, and/orother component may need to be replaced, one or more of a brush, brushholder, spring, shunt, commutator, collector ring, and/or othercomponent may need to be inspected, and/or maintenance may need to beperformed. It would be advantageous to monitor one or more components ofan electrical device in order to observe the occurrence of an anomalousand/or threshold condition. Furthermore, it would be advantageous toalert an operator and/or technician of the occurrence of an anomalousand/or threshold condition and/or schedule technician intervention.

SUMMARY

The disclosure is directed to monitoring apparatus, assemblies, systemsand methods of monitoring the wear of a brush in a brush holder assemblyand/or the condition of a slip ring of an electrical device using asensor.

An example system for monitoring the wear state of a carbon brushincludes a brush holder assembly including a carbon brush having a firstend, a second end opposite the first end, and a length measured from thefirst end to the second end. The length is diminished from an initiallength as the first end of the carbon brush wears away during use. Thebrush holder assembly also includes a wear state monitor coupled to thecarbon brush. The wear state monitor includes a sensor. The wear statemonitor is configured to rotate as the length of the carbon brushdiminishes. The sensor is configured to measure an angular displacementof the wear state monitor as the wear state monitor rotates. Themeasured angular displacement of the wear state monitor correlates to anamount of diminution in the length of the carbon brush.

In addition or alternatively, the brush holder assembly includes aspring having a first end and a second end, with the first end coupledto the wear state monitor. The spring is configured to provide a forceurging the carbon brush into contact with a rotating conductive surfaceof an electrical machine.

In addition or alternatively, the wear state monitor includes acircumferential groove extending around a circumferential outer surfaceof the wear state monitor, and wherein the spring is disposed within thegroove.

In addition or alternatively, a coiled portion of the spring isconfigured to wrap around a circumferential outer surface of the wearstate monitor as the wear state monitor rotates.

In addition or alternatively, the brush holder assembly includes aspring having a coiled portion and an elongate portion extending fromthe coiled portion, wherein the wear state monitor is positioned withinthe coiled portion.

In addition or alternatively, the wear state monitor includes acircumferential groove extending around a circumferential outer surfaceof the wear state monitor, and wherein the coiled portion of the springis disposed within the groove.

In addition or alternatively, the brush holder assembly includes aspacer positioned between the coiled portion of the spring and thesecond end of the carbon brush.

In addition or alternatively, the spacer includes a magnet, and thesensor is a Hall effect sensor sensing a magnetic field of the magnet.

In addition or alternatively, the spacer defines a concave cradle,wherein the coiled portion of the spring rests in the cradle.

In addition or alternatively, the wear state monitor rotates about anaxis of rotation, wherein the axis of rotation is a fixed distance fromthe second end of the carbon brush as the wear state monitor rotates.

In addition or alternatively, the sensor is a rotary magnetic encoder.

In addition or alternatively, the sensor is configured to transmit awireless signal to a site monitor, and wherein the wireless signal isconfigured to provide information relating to diminution in length ofthe carbon brush.

Another example system for monitoring the wear state of a carbon brushincludes a brush holder coupled to a handle. The brush holder includesan opening, and a carbon brush is disposed within the opening of thebrush holder. The system also includes a spring applying a force againstthe carbon brush to translate the carbon brush within the opening as afirst end of the carbon brush wears away during use. The system furtherincludes a wear state monitor positioned within a coiled portion of thespring, the wear state monitor configured to rotate as the first end ofthe carbon brush wears away.

In addition or alternatively, the system further includes a sensordisposed within a housing of the wear state monitor, wherein the sensoris configured to measure an angular displacement of the wear statemonitor as the wear state monitor rotates.

In addition or alternatively, the measured angular displacement of thewear state monitor correlates to an amount the carbon brush has wornaway.

In addition or alternatively, the wear state monitor rotates about anaxis of rotation, wherein the axis of rotation is a fixed distance froman upper surface of the carbon brush as the wear state monitor rotates.

In addition or alternatively, the spring includes an elongate portionextending from the coiled portion of the spring along a side surface ofthe carbon brush.

In addition or alternatively, an end of the elongate portion of thespring is removably coupled to the brush holder.

In addition or alternatively, the wear state monitor includes acircumferential groove extending around a circumferential outer surfaceof the wear state monitor, and wherein the coiled portion of the springis disposed within the groove.

In addition or alternatively, a portion of the spring is configured towind up around a circumferential outer surface of the wear state monitoras the wear state monitor rotates.

In addition or alternatively, the wear state monitor is configured torotate through an arc angle as the carbon brush wears away, and whereinthe arc angle correlates to the amount the carbon brush wears away.

Another embodiment is a method for monitoring the wear state of a carbonbrush. The method includes determining an angular displacement of a wearstate monitor positioned adjacent to the carbon brush with a sensor asthe wear state monitor rotates as a length of the carbon brushdiminishes during use, and determining a wear state of the carbon brushbased on the angular displacement of the wear state monitor.

In addition or alternatively, the method further includes comparing thewear state of the carbon brush to a threshold value.

In addition or alternatively, the method further includes communicatingan indication of the wear state of the carbon brush to a user.

The above summary of some embodiments, aspects, and/or examples is notintended to describe each embodiment or every implementation of thepresent disclosure. The figures and the detailed description whichfollows more particularly exemplify these embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The aspects of the disclosure may be more completely understood inconsideration of the following detailed description of variousembodiments in connection with the accompanying drawings, in which:

FIG. 1 shows an illustrative view of an exemplary brush monitoringsystem positioned adjacent a component of an electrical machine;

FIG. 2 shows an example wear state monitor and spring positionedadjacent a spacer on a brush;

FIG. 3 shows an exploded view of the brush holder assembly componentsshown in FIG. 2;

FIG. 4 shows an end view of the wear state monitor and spring shown inFIG. 4;

FIG. 5 shows a side view of the wear state monitor and spring shown inFIG. 4;

FIG. 6 shows an exploded view of the wear state monitor shown in FIG. 4;

FIGS. 7 and 8 show side views of an illustrative brush holder assemblyat a first wear state and a second wear state.

While the aspects of the disclosure are amenable to variousmodifications and alternative forms, specifics thereof have been shownby way of example in the drawings and will be described in detail. Itshould be understood, however, that the intention is not to limitaspects of the disclosure to the particular embodiments described. Onthe contrary, the intention is to cover all modifications, equivalents,and alternatives falling within the spirit and scope of the disclosure.

DETAILED DESCRIPTION

For the following defined terms, these definitions shall be applied,unless a different definition is given in the claims or elsewhere inthis specification.

All numeric values are herein assumed to be modified by the term“about”, whether or not explicitly indicated. The term “about” generallyrefers to a range of numbers that one of skill in the art would considerequivalent to the recited value (i.e., having the same function orresult). In many instances, the term “about” may be indicative asincluding numbers that are rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numberswithin that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4,and 5).

Although some suitable dimensions, ranges and/or values pertaining tovarious components, features and/or specifications are disclosed, one ofskill in the art, incited by the present disclosure, would understanddesired dimensions, ranges and/or values may deviate from thoseexpressly disclosed.

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” include plural referents unless the contentclearly dictates otherwise. As used in this specification and theappended claims, the term “or” is generally employed in its senseincluding “and/or” unless the content clearly dictates otherwise.

The following detailed description should be read with reference to thedrawings in which similar elements in different drawings are numberedthe same. The detailed description and the drawings, which are notnecessarily to scale, depict illustrative embodiments and are notintended to limit the scope of the disclosure. The illustrativeembodiments depicted are intended only as exemplary. Selected featuresof any illustrative embodiment may be incorporated into an additionalembodiment unless clearly stated to the contrary.

FIG. 1 illustrates an exemplary brush monitoring system 100 that mayinclude a brush holder assembly 110, a site monitor 120 and/or a remotemonitoring site 140 including a remote monitoring device 150, 160. Insome cases, the brush holder assembly 110 may substantially resemble abrush holder assembly as described in U.S. Pat. No. 7,034,430, entitled“BRUSH HOLDER APPARATUS, BRUSH ASSEMBLY, AND METHOD”, which is hereinincorporated by reference in its entirety. However, the illustrativebrush monitoring system 100 may be amenable to any of various brushholder assembly configurations. Thus, the intention is that theillustrative brush monitoring system 100 may be used in conjunction withany desired brush holder assembly configurations of an electricaldevice, such as an industrial electrical generator. For example, theillustrative brush monitoring system 100 may be used with brush holderassemblies, brush holders and/or brushes disclosed in U.S. Pat. Nos.6,731,042; 5,753,992; 5,621,262; 5,463,264; 5,397,952; and 5,256,925;each of which is incorporated herein by reference.

FIG. 1 illustrates a brush 24 including a first end surface 34 and asecond end surface 35 and a length extending therebetween. The secondend surface 35 may be in electrical contact with a conductive surface 12of a rotating component 15 of an electrical machine (e.g., a collectorring, a slip ring, or a commutator) and conduct electrical currenttherefrom. Further, FIG. 1 illustrates that, in some examples, one ormore sides of the brush 24 may be surrounded by a brush holder 22 (e.g.,a brush box), whereby the brush holder 22 may include a plurality ofguiding surfaces for guiding linear or longitudinal movement of thebrush 24 toward the conductive surface 12 of the rotating component 15.In other words, the brush 24 may translate linearly within an aperturedefined by the plurality of guiding surfaces of the brush holder 22 asthe brush 24 wears. In some embodiments it is contemplated that thebrush holder 22 may not take on the form of a box, but may include oneor a plurality of guiding surfaces, such as channels, posts or columns,abutting and/or encompassing one or more sides of the brush 24 and/orextending into or through the brush 24, or a portion thereof, forguiding linear or longitudinal movement of the brush 24.

FIG. 1 further illustrates that the brush holder 22 may be secured to amounting beam 26 configured and adapted to be mounted to anotherstructure, such as a mounting block 70. The brush holder assembly 110may be configured to place the brush 24 in contact with the conductivesurface 12, such as the surface of the rotating component 15 of theelectrical machine. The brush 24 may extend from the lower edge of thebrush holder 22 such that the second end surface 35 of the brush 24engages the conductive surface 12. The mounting beam 26 may include anover-center engagement mechanism, a slotted or channeled engagementmechanism for sliding engagement, or other mechanism for easily engagingand disengaging the brush 24 from a conductive surface 12. In otherembodiments, the brush holder assembly 110 may include a brush holder 22rigidly mounted to another structure holding the brush holder 22stationary, or mounted to another structure in any desired arrangement.For example, in some embodiments the brush holder 22 may be bolted orwelded to a stationary structure. Some such brush holders are disclosedin U.S. Pat. Nos. 6,731,042; 5,753,992; 5,621,262; 5,463,264; 5,397,952;and 5,256,925; which are incorporated herein by reference.

As shown in FIG. 1, the mounting beam 26 may include an upper beammember 27 and a lower beam member 28 hingedly or pivotedly coupled toone another. When the upper beam member 27 and the lower beam member 28are aligned with one another (e.g., the longitudinal axis of the upperbeam member 27 is parallel with the longitudinal axis of the lower beammember 28), the brush holder 22 may be considered to be in an engaged,or locked, position such that the brush 24 may be contiguous with or incontact with the conductive surface 12. When the upper beam member 27 istilted from the lower beam member 28 (e.g., the longitudinal axis of theupper beam member 27 is oblique to the longitudinal axis of the lowerbeam member 28), the brush holder 22 may be considered to be in adisengaged, or unlocked, position such that the brush 24 may benon-contiguous with, spaced from, or otherwise not in direct electricalcontact with the conductive surface 12. The mounting beam 26 may beremovably coupled to the mounting block 70 during operation. In someembodiments, the mounting beam 26 may slidably engage with, interlockwith, or otherwise be removably coupled to the mounting block 70. Themounting block 70 may be coupled to, secured to, or otherwise extendfrom another structure which maintains the mounting block 70 stationarywith respect to (i.e., a fixed distance from) the conductive surface 12,for example.

In some embodiments, a handle 21 may be attached to the brush holder 22to facilitate engagement and disengagement of the brush 24 from theconductive surface 12. For example, the handle 21 may be attached to theupper beam member 27 such that movement of the handle 21 actuates (e.g.,pivots, slides, releases) the upper beam member 27 relative to the lowerbeam member 28. The handle 21 may be a removable handle or the handle 21may be permanently attached to the upper beam member 27 or anotherportion of the brush holder 22.

FIG. 1 further illustrates that the brush holder assembly 110 mayinclude a wear state monitor 50 and a spacer 30. The spacer 30 may beattached to the first end surface 34 of the brush 24. Additionally, FIG.1 illustrates that the wear state monitor 50 may be coupled to a spring29. In some examples, a portion of the spring 29 may be coiled around aportion of the wear state monitor 50, with an elongate portion of thespring extending from the coiled portion. Further detailed discussion ofthe wear state monitor 50, the spacer 30 and the spring 29 followsbelow.

In some examples the wear state monitor 50 may include one or moresensors which collect and/or measure a variety of parameterscorresponding to the “wear state” of the brush 24. For example, the wearstate monitor 50 may include one or more sensors which measure and/orcommunicate the extent to which the brush 24 wears away while in contactwith the conductive surface 12 of the rotating component 15. In someexamples, the sensor(s) may also measure the vibration and/ortemperature of the brush holder assembly 110 (including individualcomponents thereof) and/or the brush 24, and/or electrical currentpassing through the brush 24, for instance.

In some cases, the wear state monitor 50 may be positioned adjacent to asurface of a component of the brush holder assembly 110, different thanthe spring 29. For example, the wear state monitor 50 may be positionedon or adjacent to the brush holder 22, the lower beam member 28, theupper beam member 27 and/or on or adjacent to the handle 21 of the brushholder assembly 110. In some cases, the wear state monitor 50 may bepermanently and/or removably incorporated into a portion of the handle21 or other component of the brush holder assembly 110. In someexamples, the wear state monitor 50 may be free from the spring 29.

As described above, in some examples the wear state monitor 50 may bemounted adjacent a surface of the spring 29 or otherwise within thespring 29, such as within a coiled portion of the spring 29. The spring29 may include a constant force spring, which provides tension to thebrush 24, the wear state monitor 50 or both the brush 24 and the wearstate monitor 50 to bias the brush 24 toward and in contact with theconductive surface 12 of the rotating component 15. In other words, thespring 29 may include a coiled portion designed to provide a force toengage the brush 24 with a rotating component of an electrical machine,such as a slip ring, a commutator, and the like.

In some examples, the spring 29 may be attached to a portion of thebrush holder 22 and/or the mounting beam 26 of the brush holder assembly110. In some instances, a first end 32 of the spring 29 may be removablycoupled to the brush holder and/or the mounting beam 26 with an elongateportion of the spring 29 extending along a side surface of the brush 24,between the brush 24 and the mounting beam 26. Thus, in someembodiments, an elongate portion of the spring 29 may extend along oneside surface of the brush 24 between the brush 24 and the mounting beam26 of the brush holder assembly 110 up to the coiled portion of thespring 29 positioned above the upper surface 34 of the brush 24. Theopposite, second end 33 of the spring 29 may be located at the interiorof the coiled portion of the spring 29.

In some cases, the wear state monitor 50 may also include one or moreindicators 55 (e.g., one or more light emitting diodes (LEDs), aspeaker, or a combination of LEDs and/or speakers) for communicatingwear state information to a user. In some instances, the wear statemonitor 50 may be capable of communicating information about the wearstate of the brush 24 and/or the rotating component 15 to a user via theindicators 55. In some cases, the wear state monitor 50 may be capableof receiving messages from an external device, such as the site monitor120 and/or a programming device located at the same site or at a remotelocation (e.g., a computer 150, a tablet 160, a smart phone, etc.). Themessages may include commands, such as commands to send wear stateinformation about the brush 24 and/or the rotating component 15, orcommands for modifying information used by the wear state monitor 50.For example, a user may desire to modify one or more thresholds used todetermine the wear state information of the brush 24 and/or the rotatingcomponent 15, and/or to reprogram the wear state monitor 50 bydownloading instructions, tables and/or the like.

As described above, in some examples the wear state monitor 50 maymeasure and/or collect information regarding the wear state of the brush24. In particular, the wear state monitor 50 may be designed to measureand collect information regarding the extent to which the second endsurface 35 of the brush 24 contacting the conductive surface 12 has wornaway (i.e., the amount of diminution in length of the brush 24 at sometime from its initial length when installed in the brush holder assembly110). It can be appreciated that as the second end surface of the brush24 maintains contact with the rotating component 15, the second endsurface 35 of the brush 24 may wear away, thereby shortening the overalllength of the brush 24.

As described above, the spring 29 may apply a force to the brush 24which is directed linearly along the aperture defined by the brushholder 22. Further, as the brush 24 decreases in length within the brushholder 22, the wear state monitor 50 may rotate within the coil of thespring 29 while the axis of rotation of the wear state monitor 50translates linearly with linear translation of the brush 24 toward theconductive surface 12 of the rotating component 15. Additionally, asensor may be positioned within the wear state monitor 50 and maymeasure and collect data representing the extent (e.g., total angulardistance and/or total arc length) of rotation of the wear state monitor50 from its initial position when the brush 24 was installed in thebrush holder assembly 110, or any other duration desired. It can beappreciated that the amount of rotation measured by the sensor(positioned within the wear state monitor 50) may be equivalent,proportional, or otherwise representative of the linear or longitudinalmovement of the brush 24 as it translates (e.g., shortens) within thebrush holder 22, and thus equivalent, proportional, or otherwiserepresentative of the amount of diminution of the brush 24 from itsinitial length.

In some cases, the sensor may associate the rotation of the wear statemonitor 50 with a wear state of the brush 24 and/or a wear state of theconductive surface 12 and/or the rotating component 15. The value (e.g.,amount of rotation of the wear state monitor 50) measured by the sensormay correspond to the position of the first end of the brush 24 relativeto the conductive surface 12 of the rotating component 15. In somecases, the value measured by the sensor may correspond to a valueobtained over any desired time interval or duration of wear of the brush24. It can be appreciated that the value (e.g., amount of rotation ofthe wear state monitor 50 from its initial position) may be compared toone or more predetermined threshold values to determine a wear state ofthe brush 24 and/or other diagnostic information about the machine.

For example, in some cases the wear state monitor 50 (including thesensor positioned therein) may be configured to monitor a vibration ofthe brush 24. Vibration of the brush 24 may be due to one or moreimperfections, wear or other deformation of the rotating component 15 ofthe electrical machine. For example, a slip ring may deform or may wearunevenly to cause one or more portions of the slip ring to be out ofround. As the brush 24 encounters these defects at one or more positionsduring a revolution of the rotating component 15, the defects may causethe brush 24 to vibrate at a rate corresponding to the rotation speedand/or the number of defects at the conductive surface 12 of therotating component 15 (e.g., a slip ring, a commutator, etc.). In someexamples, the transient angular displacement of the wear state monitor50 may correspond and/or correlate to a threshold change in vibration orother deformation of the rotating component 15 of the electricalmachine. As used herein, “transient angular displacement” meansmomentary change in the rotational orientation of the wear state monitor50 in an oscillating fashion. Therefore, in some examples, informationcorresponding to the transient angular displacement (which maycorrespond to a threshold change in vibration) of the wear state monitor50 may be collected and transmitted to the site monitor 120 to determineif the brush 24 is experiencing excessive vibration.

Similarly, it can be appreciated that the sensor positioned within thewear state monitor 50 (or a separate temperature sensor) may measure andcollect information associated with a temperature of the brush 24, othercomponents of the electrical machine and/or the ambient air temperaturesurrounding the brush holder assembly 110. Further, the collectedtemperature values may be monitored and/or compared to one or morepredetermined temperature thresholds, whereby the temperature thresholdsmay trigger the sensor to send a signal to the site monitor 120indicative of the need for inspection and/or maintenance to be performedon one or more components of the electrical machine. For example, insome instances, the temperature threshold may be set to trigger a signalwhen the measured temperature exceeds a threshold temperature, such as athreshold temperature of 125 degrees Celsius. In other words, when thetemperature sensor measures a temperature (e.g., ambient airtemperature, temperature of a component of the electrical machine, etc.)greater than 125 degrees Celsius, it may send a signal to the sitemonitor 120 alerting personnel of the need for inspection and/ormaintenance to be performed on one or more components of the electricalmachine. In other instances, the threshold temperature may be set in arange of 100 degrees Celsius to 140 degrees Celsius, in a range of 110degrees Celsius to 130 degrees Celsius, or in a range of 120 degreesCelsius to 130 degrees Celsius, for example.

In some cases, the site monitor 120 may be positioned near theelectrical machine to monitor the wear state of one or more brush holderassemblies 110 and/or the wear state of the slip ring or other rotatingcomponent of the electrical machine. The site monitor 120 may be capableof monitoring the wear states of the brush 24 of the brush holderassembly 110. In some cases, the site monitor 120 may be capable ofmonitoring the movement of the brushes 24 of two or more brush holderassemblies 110 associated with one or more electrical machines. Forexample, the site monitor 120 may be communicatively coupled to one ormore, or a plurality of wear state monitors 50 associated with aparticular electrical machine, such as the wear state monitor 50 of thebrush holder assembly 110 via a communication link 115 (e.g., a wirelesslink). The site monitor 120 may be configured to receive processed dataand/or raw data providing information about the wear state of the brush24 and/or the rotating component 15. For example, the site monitor 120may receive information about a value received from the sensorcorresponding to the amount of rotation of the wear state monitor 50from its initial position at some temporal occasion after the brush 24has been installed on the electrical machine. However, in otherexamples, the site monitor 120 may receive information about a valueobtained by the sensor and a comparison between the value and one ormore predetermined thresholds. In some cases, the communication link 115may include a radio frequency (RF) communication link, an audio-basedcommunication link (e.g., an ultrasonic communication link), and/or anoptical communication link (e.g., an infrared (IR) communication link, avisible light communication link, etc.). In some cases, the site monitor120 may be configured to predict or determine an estimated projection ofa condition of the brush 24 into the future.

In some examples, the wear state monitor 50 may be configured tocommunicate the wear state information about the brush 24 to the sitemonitor 120 using a predetermined schedule (e.g., once per hour orhourly, once per day or daily, once per week or weekly, twice per week,etc.). In some examples, the wear state monitor 50 may provide the wearstate information about the brush 24 and/or the rotating component 15 ofthe electrical machine to the site monitor 120 in response to a commandreceived from the site monitor 120 and/or the remote monitoring device150, 160. Additionally, the site monitor 120 may be programmed toreceive wear state information about the brush 24 at predeterminedintervals. In some cases, the predetermined intervals may be fixed at aparticular value (e.g., once per hour or hourly, once per day or daily,once per week or weekly, twice per week, etc.) and in other cases, theintervals may change after a particular wear state has been reached. Forexample, the site monitor 120 may be configured to receive wear stateinformation from the wear state monitor 50 at a first time interval,such as once per day, until one or more brushes 24 and/or the rotatingcomponent 15 reach a wear state approaching the replacement wear state.At that point, the wear state monitor 50 may sample the wear stateinformation from the brush 24 at a second shorter time interval, such ashourly. Thus, the wear state information from the wear state monitor 50may be communicated to the site monitor 120 at first frequency until thebrush 24 reaches a first wear state, and thereafter, the wear stateinformation may be communicated to the site monitor 120 at a secondfrequency greater than the first frequency.

The site monitor 120 may output an indication of the condition and/orprojected condition of the brush 24. In some cases, the indication maybe configured to alert an operator, technician and/or other personnelthat the brush 24 and/or the rotating component 15 are sufficiently wornand/or needs to be replaced, the brush 24 and/or the rotating component15 are damaged, failure has occurred or is imminent, or othermaintenance or inspection may need to be performed. In some embodiments,the indication may be used for scheduling maintenance or inspection,sending personnel to perform maintenance or inspection, ordering and/orscheduling distribution/delivery of a replacement brush or other part,routing maintenance personnel and/or product delivery to a specifiedlocation, or arranging for other notification and/or scheduling tasks beperformed.

The brush monitoring system 100 may also be used to identify and/ornotify other key maintenance, failure of the brush holder assembly 110and/or other anomalous conditions. For example, incidents of excessheating, arcing or excess vibration, which may indicate a need toperform maintenance and/or disrupt operation of the electricalequipment, may be identified and/or assessed by one or more componentsof the brush monitoring system 100. The wear state monitor 50, the sitemonitor 120 and/or the remote monitoring device 150, 160 may carry outan appropriate response to respond to an identified anomalous conditionin an attempt to rectify the anomalous condition. In some cases, anoperator may carry out an appropriate response to respond to ananomalous condition identified with the brush monitoring system 100 inan attempt to rectify the anomalous condition.

In some cases, the site monitor 120 may be communicatively coupled by awireless link 125 and/or wired link 127 to a network 130. The sitemonitor 120 may be capable of communicating information about the wearstate of one or more brushes 24 to a remote monitoring device 150, 160at a remote monitoring site 140 via the network 130 and one or morewired 137 and/or wireless 135 communication links. The wired link 127,137 and/or wireless link 125, 135 communication links may be configuredto operate using one or more standardized communication protocols (e.g.,Ethernet, Ethernet/IP, BACnet, Modbus, LonWorks, etc.), or proprietarycommunication protocols. Examples of a remote monitoring system aredescribed in U.S. Pat. No. 7,705,744, entitled “MONITORING SYSTEMS ANDMETHODS FOR MONITORING THE CONDITION OF ONE OR MORE COMPONENTS OF ANELECTRICAL DEVICE”, U.S. Pat. No. 8,618,943, entitled “BRUSH HOLDERASSEMBLY MONITORING APPARATUS, ASSEMBLY, SYSTEM AND METHOD”, and U.S.Pat. No. 9,252,643, entitled “SYSTEM AND METHOD FOR MONITORING THESTATUS OF ONE OR MORE COMPONENTS OF AN ELECTRICAL MACHINE”, which areherein incorporated by reference in their entirety. The remotemonitoring site 140 may include one or more remote monitors, such as apersonal computer 160, a workstation, a laptop, a tablet 150, a smartphone or the like, for collecting data and/or analyzing data receivedfrom one or more user sites.

The remote monitoring devices and/or site monitor 120 may be integratedinto a maintenance program for a brush holder assembly 110, such thatthe site monitor 120 may be configured to monitor at least a conditionof one or more components of the brush holder assembly 110. To do so,the remote monitors and/or the site monitor 120 may be configured toidentify each brush holder assembly 110 on a particular machine or at aparticular site and/or store an installation date and any servicingdates for each brush holder assembly 110 and/or components thereof, suchas the installation date of a brush 24 in the brush holder assembly 110.In some examples, the wear state monitor 50 (or other sensor of thebrush holder assembly 110) may output a signal to the site monitor 120indicating that a brush 24 or other component of the electrical machinehas been removed and/or replaced, and/or an indication that a new brush24 has been installed. Component replacement information may becollected and monitored by the wear state monitor 50, one or moresensors of the brush assembly 110 and/or the site monitor 120.

In some cases, one or more parameters received from the wear statemonitor 50 associated with a brush holder assembly 110 may be monitoredover time to determine trending information about a brush 24 and/or arotating component 15 of the electrical machine. For example, the sitemonitor 120 and/or the remote monitors may determine trend information,that may include an average lifetime for a brush 24 installed in aparticular brush holder assembly 110 and/or for a particularinstallation position on an electrical machine. The site monitor 120and/or the remote monitors may be configured to store information aboutthe position of a brush 24 when the brush 24 and/or brush holderassembly 110 is first installed on an electrical machine. By monitoringthe final position and/or replacement date of a brush 24 along with theinitial position and/or installation date each time a brush 24 isreplaced and a new brush 24 is installed in the brush holder assembly110, information may be gathered about a wear state of the rotatingcomponent 15. For example, a slip ring, or other rotating component ofthe electrical machine, may have an initial outer diameter measurement.Over time, with wear including normal wear and/or due to environmentalconditions (e.g., humidity, temperature, contaminants includingabrasives, etc.) a wear state associated with the thickness and/or outerdiameter of the rotating component 15 may be measured and/or predicted.In some cases, preventative measures to improve the lifetime of thebrush 24 and/or the rotating component 15 may be obtained by analysis ofthe information received from the one or more wear state monitors 50.For example, a user may be advised to adjust one or more environmentalconditions for a space near the electrical machine, such as atemperature, a humidity level and/or a contaminant level.

FIG. 2 illustrates the wear state monitor 50, spring 29 and spacer 30shown in FIG. 1, positioned above an upper surface of a carbon brush 24.FIG. 3 illustrates an exploded perspective view of the wear statemonitor 50, spring 29 and spacer 30 as described above in FIG. 2. Forclarity, FIG. 3 illustrates the wear state monitor 50, spring 29 andspacer 30 after having been rotated 180 degrees as compared with theirorientation depicted in FIG. 1 and FIG. 2.

As illustrated in FIG. 2 in some examples the wear state monitor 50 andspring 29 may be nested within the spacer 30, such as within a concavecradle of the spacer 30. The spacer 30 may be positioned between thecoiled portion of the spring 29 and the upper or first end surface 34 ofthe carbon brush 24. In some instances, the spacer 30 may be attached tothe first end surface 34 of the brush 24 such that the spacer 30 moveswith the brush 24. For example, as shown in FIG. 3, the spacer 30 mayinclude one or more projections, such as pin members 38, designed toengage bores extending into the brush 24 from the first end surface 34(shown in FIG. 1) of the brush 24. For example, each of the pin members38 may be designed to extend into a corresponding bore located withinthe first end surface 34 of the brush 24. It can be appreciated thatengagement of the pin members 38 within their respective bore functionsto secure the spacer 30 to the brush 24. In other instances, the spacer30 may include a different engagement feature configured to mate with acomplementary engagement feature in the first end surface 34 of thebrush. For example, the spacer 30 may include one or more railsconfigured to extend into corresponding channels formed in the first endsurface 34 of the brush 24.

The wear state monitor 50 may include a first end region 40, a secondend region 42 and a medial region 43 (see FIG. 4) extendingtherebetween. The medial region 43 may be generally cylindrical, orother such shape designed to facilitate integration into a brush holderassembly 110 or other mounting location within the brush holder assembly110. In some instances, the medial region 43 may have a cylindricalcircumferential surface. Each of the first end region 40 and the secondend region 42 may extend radially outward from the circumferentialsurface of the medial region 43, thereby creating a groove or recessedarea (further illustrated in FIG. 4) in which the coiled portion of thespring 29 may be positioned between the first end region 40 and thesecond end region 42.

As discussed above, the medial portion 43 of the wear state monitor 50may be designed to be captured within the coiled portion of the spring29. In other words, a portion of the spring 29 (i.e., the coiledportion) may be coiled (e.g., wrapped) around the medial region 43 ofthe wear state monitor 50. As shown in FIG. 2, the first end region 40and the second end region 42 may provide a shoulder on opposing sides ofthe coiled portion of the spring 29 to ensure that the spring 29 doesnot slip out of the groove defined between the first end region 40 andthe second end region 42. It can be appreciated that the first endregion 40 and/or the second end region 42 may be removable, or otherwiseconfigurable, to allow the wear state monitor 50 to be mounted within acoiled portion of different sized springs. For example, the removableand/or configurable first end region 40 and/or second end region 42, mayallow the wear state monitor 50 to be mounted within a coiled portion ofa spring having a first width and a first coil diameter and/or a springhaving a second different width and/or a second different coil diameter.

As discussed above, a sensor may be positioned within the wear statemonitor 50 and may measure and collect data representing a currentrotational position of the wear state monitor 50 which can be used todetermine the extent (e.g., total angular distance and/or total arclength) of rotation of the wear state monitor 50 from its initialposition whereby the amount of rotation measured by the sensor(positioned within the wear state monitor 50) may be equivalent,proportional, or otherwise representative of the linear or longitudinalmovement of the brush 24 (shown in FIG. 1) as it translates (e.g.,shortens) within the brush holder 22 (shown in FIG. 1). In particular,the sensor positioned within the wear state monitor 50 may be designedto detect the absolute angular position of the sensor relative to apermanent magnet positioned adjacent the sensor. For example, FIG. 2illustrates a magnet 14 attached to the spacer 30, or otherwiseincorporated with the spacer 30. While FIG. 2 illustrates the magnet 14approximately aligned with the central axis of the wear state monitor50, it is contemplated that the magnet 14 may be positioned along otherportions of the wear state monitor 50 and/or along other elements of thebrush holder assembly 110. FIG. 3 illustrates that, in some examples,the medial region 43 of the wear state monitor 50 may include anengagement feature such as a tab, shoulder or an opening, (not shown inFIG. 2) which may be used to facilitate a connection with or engagementwith the second end 33 of the spring 29 located on the interior of thecoiled portion of the spring 29. For example, FIG. 3 illustrates a boss(e.g., protrusion) 16 extending away from the outer surface of themedial region 43. The boss 14 may have a shape configured to mate with acorresponding opening 18 of the spring 29 proximate the second end 33 ofthe spring 29. The opening 18 may have a shape corresponding to across-sectional shape of the boss 16. For example, the boss 16 may havea circular cross-sectional shape designed to mate with a circular shapeof the opening 18. However, while FIG. 3 illustrates the boss 16 and theopening 18 having a circular shape, other shapes are contemplated. Forexample, the boss 16 and the opening 18 may include square, ovular,rectangular, star, triangular, or any other geometric shape. It can beappreciated that engagement of the boss 16 with the opening 18 mayrotationally fix the wear state monitor 50 with the coiled portion ofthe spring 29 such that rotational movement (e.g., coiling) of thecoiled portion of the spring 29 correspondingly rotates the wear statemonitor 50 an equal amount.

In other embodiments, the outer surface of the medial region 43 mayinclude a shoulder or raised edge configured to engage the second end 33of the spring 29 when the coiled portion of the spring 29 is coiledaround the medial region 43. In some instances, the second end 33 of thespring 29 may be trapped underneath the layers of the coiled spring 29wound thereover, which may apply a radially inward compressive force onthe second end 33 of the spring 29 to maintain the second end 33 of thespring 29 against the surface of the medial region 43, ensuring thesecond end 33 of the spring 29 remains rigidly fixed to the wear statemonitor 50.

FIG. 3 further illustrates that the first end of the spring 32 may befolded back on itself to form a tab, wherein the tab is designed to beremovably coupled to the brush holder and/or the mounting beam 26 (shownin FIG. 1). In other words, the tab 19 may be designed to engaged (e.g.,be inserted into) a portion of the brush holder and/or the mounting beam26.

As illustrated in FIG. 3, the spacer 30 may include one or more arcuatesurfaces 36 defining a concave cradle designed to mate with thecircumferential profile of the wear state monitor 50. In other words,the spacer 30 may include one or more concave surfaces 36 having aradius of curvature that substantially matches the radius of curvatureof the outer surface of the wear state monitor 50. Thus, a portion ofthe wear state monitor 50 may be positioned in the concave cradle of thespacer 30. The spacer 30 may be positioned between the coiled portion ofthe spring 29 and the upper surface of the brush 24 to space the coiledportion of the spring 29 away from the brush 24.

Additionally, FIG. 3 illustrates that the spacer 30 may include aprojection 34 designed to engage the second end region 42 of the wearstate monitor 50. It can be appreciated that the second end region 42may include a recess (not shown) which is designed to mate with theprojection 34 and permit rotational movement of the wear state monitor50 about a rotational axis aligned with the central axis of theprojection 34. The engagement of the projection 34 within the recess ofthe second end portion may provide additional securement between thewear state monitor 50 and the spacer 30 while permitting rotationalmovement therebetween. Thus, it can be appreciated the projection 34 maycooperate with the arcuate surfaces 36 of the concave cradle to permitthe wear state monitor 50 to rotate (as described above) when engagedwith the spacer 30.

FIG. 4 illustrates an end view of the wear state monitor 50 includingthe first end region 40, the second end region 42 and the medial region43 extending therebetween. As discussed above, FIG. 4 illustrates theouter peripheral surfaces of both the first end region 40 and the secondend region 42 extending radially outward beyond the cylindricalcircumferential surface of the medial region 43. As described above, theinner surfaces of each of the first end region 40, the second end region42 and the circumferential surface of medial region 43 may define agroove in which the spring 29 may be positioned, with the inner surfacesof the first and second end regions 40, 42 forming shoulders.

FIG. 5 shows a side view of the wear state monitor 50 and the spring 29described above. FIG. 5 illustrates that spring 29 may include anelongate portion extending away from the wear state monitor 50 wherebythe first end 32 of the spring 29 extends past the outer circumferentialsurface of the wear state monitor 50. As noted above, the first end 32of the spring 29 (including tab 19 described above) may be removablycoupled to the brush holder and/or the mounting beam 26 with theelongate portion of the spring 29 extending along a side surface of thebrush 24, between the brush 24 and the mounting beam 26. Additionally,FIG. 5 illustrates spring 29 wrapping around the medial region 43 of thewear state monitor 50. For example, the dashed line represents thespring 29 wrapping around the medial region 43 of the wear state monitor50, whereby the second end 33 of the spring 29 is coupled to orotherwise in contact with the wear state monitor 50, such as via theboss 16 and opening 18 connection, as described above with respect toFIG. 3.

FIG. 6 illustrates an exploded view of the wear state monitor 50described above. As illustrated in FIG. 6, the wear state monitor 50 mayinclude an exterior housing 52. The exterior housing 52 may include aninner cavity 54. The cavity 54 may be configured to contain one or moreinternal components of the wear state monitor 50. The wear state monitor50 may also include a housing lid 60 configured to mate with theexterior housing 52. In other words, the lid 60 may be designed to berigidly attached to the exterior housing 52. In other instances, theexterior housing 52 may be adhesively bonded or snap fit to the lid 60to secure the exterior housing 52 and the lid 60 together. Further, thelid 60 may include an aperture 71 extending through the entire wallthickness of the lid 60.

Additionally, the wear state monitor 50 may include a button 59. In someinstances, the button 59 may be a Viton button. The button 59 may beutilized to pair the wear state monitor 50 to another device via aBluetooth connection, for example. Further, it can be appreciated that aportion of the button 59 may be designed to project through the aperture71 of the lid 60, thereby making the button 59 accessible to depress andpair the wear state monitor 50 to another device via a Bluetoothconnection. When the exterior housing 52 is engaged with the lid 60 andthe button 59, the cavity 54 created by the combination of the exteriorhousing 52, the lid 60 and the button 59 may be sealed to the outsideenvironment.

In other instances the housing 52 may include a first housing sectionand a second housing section separable from one another to expose aninterior cavity of the wear state monitor 50 housing the internalcomponents of the wear state monitor 50. In some instances, the firsthousing section and the second housing section may be hingedly connected(e.g., connected in a “clam shell” configuration), or otherwise movablerelative to one another. In such cases, when the wear state monitor 50is located within the coiled portion of the spring 29 (e.g., a helicalspring), the force provided by the spring 29 may facilitate acompression connection or snap fit connection for engaging the firsthousing section with the second housing section of the wear statemonitor 50. In other instances, the first housing section may beadhesively bonded or snap fit to the second housing section to securethe first and second housing sections together.

FIG. 6 further illustrates that the wear state monitor 50 may furtherinclude a power source 53 (e.g., one or more batteries, capacitors, orboth) and a sensor 56 (it is noted that the sensor 56 may correspond tothe sensor described above with respect to FIG. 1). The power source 53may be rechargeable and/or replaceable.

In some instances, the sensor 56 may be referred to as an angular sensor56 and/or a magnetic encoder 56. As discussed above, the sensor 56 mayproduce a signal corresponding to the rotation (e.g., the absoluteangular position) of the wear state monitor 50 relative to thestationary magnet 14 described above with respect to FIG. 2. Forexample, the sensor 56 may be able to sense a change in the magneticfield created by the magnet 14, thus determining a rotationalorientation of the wear state monitor 50. The signals provided by thesensor 56 corresponding to the rotational orientation of the wear statemonitor 50 may be compared to determine an angular displacement of thewear state monitor 50 between two temporal occasions, such as between anangular position of the wear state monitor 50 when the brush 24 isinstalled in the brush holder assembly 110 and some later time when thebrush 24 has worn. These signals (corresponding to the angulardisplacement and/or rotational orientation of the wear state monitor 50)may be communicated to the site monitor 120 via a variety ofcommunication methods. In some instances, the sensor 56 may additionallyinclude an accelerometer configured to sense dynamic vibration of thebrush 24 in the brush holder 22. For example, the sensor 56, in additionto sensing angular displacement and/or rotational orientation of thewear state monitor 50, may sense transient angular displacement of thewear state monitor 50 corresponding to dynamic vibration of the brush24.

Additionally, in some cases, the power source 53 and/or sensor 56 may belocated within the cavity 54 of the wear state monitor 50, such that thepower source 53 and/or the sensor 56 may be integrated with the wearstate monitor 50. Further, it can be appreciated that when the exteriorhousing 52 is engaged with the lid 60 and the second button member 59,both the power source 53 and the sensor 56 may be sealed within thecavity 54 formed by the combination of the exterior housing 52, the lid60 and the second button member 59.

Additionally, FIG. 6 illustrates that the wear state monitor 50 mayinclude a first foam insulation member 61 a and a second foam insulationmember 61 b. In some instances, each of the first foam insulation member61 a and the second foam insulation member 61 b may be formed fromsilicone. Other materials may be utilized to form the first foaminsulation member 61 a and/or the second foam insulation member 61 b.Further, the first foam insulation member 61 a and the second foaminsulation member 61 b may be utilized to insulate the power supply 53when positioned within the cavity 54.

In other words, when positioned inside the cavity 54, the power supply53 may be disposed between the first foam insulation member 61 a and thesecond foam insulation member 61 b.

The power source 53 of the wear state monitor 50 may be used to supplypower to one or more components of the wear state monitor 50, such asthe sensor 56, to facilitate the measurement and generation of a valuerepresentative of the angular displacement or rotation of the wear statemonitor 50 (which is proportional to the diminution in length of thebrush 24 during use, as described above). In other words, as the wearstate monitor 50 rotates in response to the diminution in length of thebrush 24 as the brush 24 wears, the sensor 56 may sense, measure andcollect the information (e.g., data) of the amount of rotation orangular displacement of the wear state monitor 50, which is proportionalto or otherwise correlates to the amount of diminution in length of thebrush 24. The wear state monitor 50 rotates about an axis of rotationpassing through the center of the wear state monitor 50. The axis ofrotation is a fixed distance from the second end 34 of the carbon brush24 as the wear state monitor 50 rotates, and thus the axis of rotationtranslates with the brush 24 as the brush 24 wears and diminishes inlength.

For example, in some instances, the sensor 56 may obtain valuescorresponding to a first position of the brush 24, at a first temporaloccasion T₀, such as an initial position of the brush 24 when the brush24 has been placed on the electrical device and having approximately nowear. In other words, the sensor 56 may be used to sense the angularposition of the wear state monitor 50 at the initial temporal occasionT₀. The sensor 56 may obtain values corresponding to a position of thebrush 24 at a later temporal occasion T₁ after the brush has been worn afirst amount. In other words, the sensor 56 may be used to sense theangular position of the wear state monitor 50 at the temporal occasionT₁. The sensor 56 may obtain additional values corresponding to afurther positions of the brush 24 at later temporal occasions T₂, T₃,T₄, etc. after the brush has been worn an additional amount. In otherwords, the sensor 56 may be used to sense the angular position of thewear state monitor 50 at the further temporal occasions T₂, T₃, T₄, etc.The angular displacement of the wear state monitor 50 between eachtemporal occasion may be used to determine the diminution in length ofthe brush 24, and thus the current wear state of the brush 24 and/orproject when the brush 24 will diminish in length to a threshold amountat a future time. In some instances the threshold amount may correspondto a brush length approximating when the brush 24 has a predeterminedamount of wear (e.g., approaching the replacement threshold, maximumallowable wear, etc.).

Additionally, in some cases, the sensor 56 may be configured to sense afirst threshold value corresponding to a first wear state of the brush24 and a second threshold value different from the first threshold valuecorresponding to a second wear state of the brush 24. For example, thefirst threshold value may include the total rotation amount or angulardisplacement of the wear state monitor 50 indicative of a wear statewhere the brush 24 should be replaced within a predetermined time period(e.g., within a week). The second threshold value may correspond to atotal rotation amount or angular displacement of the wear state monitor50 indicative of a wear state requiring the brush 24 to be replaced assoon as possible.

FIGS. 7 and 8 illustrate side views of the brush holder assembly 110shown in FIG. 1, at different temporal occasions representing differentidentifiable wear states of the brush 24. For simplicity purposes, thespacer 30 (shown in FIG. 1) has been removed from FIGS. 7 and 8.Additionally, FIGS. 7 and 8 illustrate the brush holder assembly 110including the brush holder 22 secured to the mounting beam 26, wherebythe mounting beam 26 is configured to be removably mounted to themounting block 70. Further, FIGS. 7 and 8 show the mounting beam 26including the upper beam member 27 and the lower beam member 28pivotally coupled to one another in the engaged position, as describedabove with respective to FIG. 1. FIG. 7 and FIG. 8 further illustratethe brush holder assembly 110 including a handle 21 and the conductivewires 62 attached to both the brush 24 and extending therefrom.

As discussed above and illustrated in FIGS. 7 and 8, an end region ofthe spring 29 may be coiled around a portion (e.g., the medial region)of the wear state monitor 50 while the elongate portion of the spring 29extends along a side surface of the brush 24 with the first end 32 ofthe spring 29 coupled to the mounting beam 26. Further, while notvisible in FIGS. 7 and 8, a sensor and/or power supply may be positionedwithin an interior space (e.g., a cavity) within the wear state monitor50 (as described above).

FIG. 7 illustrates a first configuration (e.g., an initial wear state)of the brush 24 at an initial temporal occasion T₀, such as when thebrush 24 of the brush holder assembly 110 is first installed on anelectrical machine. FIG. 7 illustrates the brush 24 positioned withinthe brush holder 22 (as described above with respect to FIG. 1), withthe lower surface of the brush 24 engaged with the conductive surface 12of the rotating component 15. Additionally, FIG. 7 shows that the firstend surface 34 of the brush 24 is positioned a distance X₁ from the endof the brush holder 22 nearest the handle 21 at an initial position atthe initial temporal occasion T₀. It can be appreciated that when thebrush holder assembly 110 is in an engaged position, the spring 29 mayapply a force to the first end surface 34 of the brush 24 to engage thebrush 24 with the conductive surface 12 of the rotating component 15.

For illustrative purposes, FIG. 7 includes a “rotation marker” 64 placedon the wear state monitor 50. For simplicity, the rotation marker 64 hasbeen placed on the wear state monitor 50 at approximately the “twelve 'oclock” position, but could be placed at any desired location. Therotation marker 64 need not be a visual marker, although it is possibleto include a visual marker. The rotation marker 64 may be representativeof a positional signal provided by the sensor 56 of a rotationalorientation of the wear state monitor 50.

FIG. 8 illustrates a second configuration (e.g., a second wear state) ofthe brush 24 at a later temporal occasion T₁, such as after the brush 24has engaged the conductive surface 12 of the rotating component 15 overa period of time and diminished in length. As described above, thespring 29 may continue to exert a force on the first end surface 34 ofthe brush 24 as the brush 24 wears away against the conductive surface12 of the rotating component 15. For example, FIG. 8 illustrates thefirst end surface 34 of the brush 24 positioned a distance X₂ from endof the brush holder 22 nearest the handle. It can be appreciated thatthe difference between distance “X₂” and distance “X₁” shown in FIG. 7,represents the amount of diminution in length of the brush 24 (i.e., howmuch the brush 24 has shortened in length).

Additionally, as described above, as the brush 24 translates within thebrush holder 22, the wear state monitor 50 may rotate in proportion tothe length of shortening of the brush 24. The rotation or angulardisplacement θ of the wear state monitor 50 between the initialrotational position of the wear state monitor 50 at T₀ and therotational position of the wear state monitor 50 at T₁ is illustrated inFIG. 8. Additionally, FIG. 8 shows the rotation position marker 64 in asecond position, further representing the rotation or angulardisplacement of the wear state monitor 50. It is noted that therotational axis of the wear state monitor 50 remains at a fixed distancefrom the upper surface of the brush 24 throughout the wear of the brush24.

As described above, as the wear state monitor 50 rotates in response tothe shortening of the brush 24 (e.g., the wearing of the second endsurface 35 of the brush 24), the sensor 56 may measure and collectinformation relating to the rotation or angular displacement of the wearstate monitor 50. Further, this information relating to the rotation orangular displacement of the wear state monitor 50 may be analyzed todetermine an amount of diminution in length of the brush 24, a currentwear state of the brush 24, a wear rate of the brush 24, and/or predicta future wear state of the brush 24 at a future time. Such informationand/or data regarding the state of the brush 24 may be communicated tothe site monitoring device 120 and/or a remote monitoring device 140.The remote monitoring device 140 may be located at the same and/or at adifferent geographical location from the geographical location of theelectrical machine and the site monitoring device 120.

In some cases, the wear state monitor 50, the site monitor 120 and/orthe remote monitoring device 140 may include a processor capable ofprocessing instructions for predicting a life expectancy of the brush 24and/or the rotating component 15 of the electrical machine. In somecases, the processor may be capable of processing instructions foridentifying the wear state of the carbon brush and/or identifying thewear state of the rotating electrical component (e.g., a slip ring, acommutator, etc.) of the electrical device.

Those skilled in the art will recognize that aspects of the presentdisclosure may be manifested in a variety of forms other than thespecific embodiments described and contemplated herein. Accordingly,departure in form and detail may be made without departing from thescope and spirit of the present disclosure as described in the appendedclaims.

What is claimed is:
 1. A system for monitoring the wear state of acarbon brush, comprising: a brush holder assembly, the brush holderassembly including: a carbon brush including a first end, a second endopposite the first end, and a length measured from the first end to thesecond end, wherein the length is diminished from an initial length asthe first end of the carbon brush wears away during use; a wear statemonitor coupled to the carbon brush, the wear state monitor including asensor; wherein the wear state monitor is configured to rotate as thelength of the carbon brush diminishes; wherein the sensor is configuredto measure an angular displacement of the wear state monitor as the wearstate monitor rotates; wherein the measured angular displacement of thewear state monitor correlates to an amount of diminution in the lengthof the carbon brush.
 2. The system of claim 1, further comprising aspring having a first end and a second end, the first end coupled to thewear state monitor, wherein the spring is configured to provide a forceurging the carbon brush into contact with a rotating conductive surfaceof an electrical machine.
 3. The system of claim 2, wherein the wearstate monitor includes a circumferential groove extending around acircumferential outer surface of the wear state monitor, and wherein thespring is disposed within the groove.
 4. The system of claim 2, whereina coiled portion of the spring is configured to wrap around acircumferential outer surface of the wear state monitor as the wearstate monitor rotates.
 5. The system of claim 1, further comprising aspring having a coiled portion and an elongate portion extending fromthe coiled portion, wherein the wear state monitor is positioned withinthe coiled portion.
 6. The system of claim 5, wherein the wear statemonitor includes a circumferential groove extending around acircumferential outer surface of the wear state monitor, and wherein thecoiled portion of the spring is disposed within the groove.
 7. Thesystem of claim 5, further comprising a spacer positioned between thecoiled portion of the spring and the second end of the carbon brush. 8.The system of claim 7, wherein the spacer includes a magnet, and thesensor is a Hall effect sensor sensing a magnetic field of the magnet.9. The system of claim 7, wherein the spacer defines a concave cradle,wherein the coiled portion of the spring rests in the cradle.
 10. Thesystem of claim 1, wherein the wear state monitor rotates about an axisof rotation, wherein the axis of rotation is a fixed distance from thesecond end of the carbon brush as the wear state monitor rotates. 11.The system of claim 1, wherein the sensor is a rotary magnetic encoder.12. The system of claim 1, wherein the sensor is configured to transmita wireless signal to a site monitor, and wherein the wireless signal isconfigured to provide information relating to diminution in length ofthe carbon brush.
 13. A system for monitoring the wear state of a carbonbrush, comprising: a brush holder coupled to a handle, the brush holderincluding an opening; a carbon brush disposed within the opening of thebrush holder, a spring applying a force against the carbon brush totranslate the carbon brush within the opening as a first end of thecarbon brush wears away during use; and a wear state monitor positionedwithin a coiled portion of the spring, the wear state monitor configuredto rotate as the first end of the carbon brush wears away.
 14. Thesystem of claim 13, further comprising a sensor disposed within ahousing of the wear state monitor, wherein the sensor is configured tomeasure an angular displacement of the wear state monitor as the wearstate monitor rotates.
 15. The system of claim 14, wherein the measuredangular displacement of the wear state monitor correlates to an amountthe carbon brush has worn away.
 16. The system of claim 13, wherein thewear state monitor rotates about an axis of rotation, wherein the axisof rotation is a fixed distance from an upper surface of the carbonbrush as the wear state monitor rotates.
 17. The system of claim 13,wherein the spring includes an elongate portion extending from thecoiled portion of the spring along a side surface of the carbon brush.18. The system of claim 17, wherein an end of the elongate portion ofthe spring is removably coupled to the brush holder.
 19. The system ofclaim 13, wherein the wear state monitor includes a circumferentialgroove extending around a circumferential outer surface of the wearstate monitor, and wherein the coiled portion of the spring is disposedwithin the groove.
 20. The system of claim 13, wherein a portion of thespring is configured to wind up around a circumferential outer surfaceof the wear state monitor as the wear state monitor rotates.
 21. Thesystem of claim 13, wherein the wear state monitor is configured torotate through an arc angle as the carbon brush wears away, and whereinthe arc angle correlates to the amount the carbon brush wears away. 22.A method for monitoring the wear state of a carbon brush, the methodcomprising: determining an angular displacement of a wear state monitorpositioned adjacent to the carbon brush with a sensor as the wear statemonitor rotates as a length of the carbon brush diminishes during use;and determining a wear state of the carbon brush based on the angulardisplacement of the wear state monitor.
 23. The method of claim 22,further comprising: comparing the wear state of the carbon brush to athreshold value.
 24. The method of claim 22, further comprising:communicating an indication of the wear state of the carbon brush to auser.